Influence of L-5-hydroxytryptophan and DL-p-chlorophenylalanine on neurophysiological profiles of serotonin reuptake inhibitors in rabbits.

In a previous study we noted that some drugs, which exert their action by inhibiting serotonin (5-HT) reuptake, caused different EEGraphic, behavioural and autonomic patterns. These drugs (Alaproclate, Citalopram, Fluoxetine, Fluvoxamine, Indalpine, Zimelidine) have now been studied in two groups of animals pretreated with L-5-hydroxytryptophan (L-5-HTP), the 5-HT precursor, and with DL-p-chlorophenylalanine (PCPA), a 5-HT depletor. The administration of 5-HT reuptake inhibitors, after pretreatment with L-5-HTP, caused homogeneous changes, i.e. EEG cortical desynchronization and behavioural serotonergic syndrome. No significant modifications of the parameters examined were observed in the animals of the second group (pretreated with PCPA). The possible mechanisms of action of these drugs and some aspects of the role of serotonin in the central nervous system are discussed.